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60 Hz filtering using DC8

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  • 60 Hz filtering using DC8

    I often use DC8 to filter out incidental 60 Hz hum in what are otherwise clean, on-site live recordings.

    And I have often wondered about the differences between using the EZ Clean filter, the Harmonic Reject filter, or the Continuous Noise Filter to minimize 60 Hz noise.

    The EZ Clean filter, using the 60 Hz hum reject, seems to be the easiest to use. However this filter also tries to correct for clicks and scratches when the same operative controls are set to a '0' value. Seems to be a bug I would think, in that these software functions should be absolutely inoperative if their respective control functions are set to '0'. So I have decided to not use EZ Clean for hum reduction because it occasionally alters the recorded material beyond reducing the hum level.

    But nonetheless, all these filters do the job and do it well.

    Could one explain what filter is the best to use, and why?

    Phillip
    Last edited by Craig Maier; 06-01-2019, 04:18 PM.

  • #2
    Hi,

    There is one other filter that you missed - - - the EZ Impulse filter - - - sometimes useful for 60 Hz "Buzz" having very high frequency content only.

    There are many different types of "Hum" related noises that I have witnessed. Which filter works best depends on the nature of the repetitive noise. If there are only a few harmonics of the fundamental, the Notch (or multiple notches in the Multifilter) works quite well. Or if there are more harmonics, the Harmonic Reject filter works pretty well up to around 20 harmonics (after which it gets kind of artifacty). For ease of use, there is the CNF or Auto spectrum CNF (using a high fft count for good frequency discrimination). And of course, the Line Frequency Buzz (often created by phase controlled lighting dimmers or similar electronic interference can be attenuated using the EZ Impulse filter (crackle control is quite effective for this).

    Best Suggestion - - - experiment to find the best filter based on the hum that you are dealing with.

    Craig

    ps - the EZ Clean filter controls do not go to zero which is not a bug, but the way that we designed it. The control ranges are set up to be EZ to use and thus have ranges that do something at all settings. This should not be an issue in general, but if it does, you can just use one of the more specific filters like the EZ Impulse, Expert Impulse, CNF, etc. Their controls go to zero.
    Last edited by Craig Maier; 08-29-2012, 10:09 PM.
    "Who put orange juice in my orange juice?" - - - William Claude Dukenfield

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